Power transmission



y 6, 1954 w. P. DALRYMPLE POWER TRANSMISSION 4 Sheets-Sheet 1 Filed Aug.1, 1951 frzvenior MY/I'am P Da/rymp/e 4 sheets-sheet 2 July 6, 1954 w.P. DALRYMPLE POWER TRANSMISSION Filed Aug. 1, 1951 m m8 5 Km 3 as \w%112 yen for mm um Rum u 5 I am y 1954 w. P. DALRYMPLE 2,682,788

POWER TRANSMISSION Filed Aug. 1, 1951 4 Sheets-Sheet 3 I 12 2/2 rztor51/17/1210? PDQ/lymph W. P. DALRYMPLE POWER TRANSMISSION July 6, 1954 4Sheets-Sheet 4 Filed Aug. 1, 1951 aqii rrz ey Patented July 6, 1954POWER TRANSMISSION William P. Dalrymple, Rochester, N. Y., assignor toAmerican Brake Shoe Company, Wilmington, Del., a corporation of DelawareApplication August 1, 1951, Serial No. 289,788

2 Claims.

This invention relates to power transmission mechanisms for transmittingdriving power, and particularly the invention relates to variable speedtransmission mechanisms adapted for use on wheeled vehicles such asmotorcycles and tricycles, and the like.

In my co-pending application, Serial No. 183,- 177, filed September 5,1950, there was disclosed a power unit that is particularly adaptedforuse as the propulsion means in a wheeled vehicle such as a bicycle ortricycle, and the power transmission mechanism of the present inventionis particularly intended and adapted to serve in the power unit that isdisclosed in my aforesaid co-pending application.

In power units of the aforesaid character, it is desirable that thepower transmission from the driving engine to the driven wheel becapable of assuming different speed ratios and to enable this to beaccomplished by means of a simple and effective character is the primaryobject of the present invention. In power units of the aforesaidcharacter, the driving engine must of course be disconnected from thedriven wheel when a manually starting force is applied to the engine,and another important object of the present invention is to afford atransmission mechanism where the driving engine is thus disconnectedautomatically when the vehicle is stopped.

Other important objects of the present invention are to provide a powertransmission mechanism in which the driving power from the drivingengine is first connected to a change-speed mechanism and is thenapplied through different and increasing drive ratios as the speed ofthe vehicle increases, and to accomplish the change in ultimate drivingratios in a smooth and gradual manner.

- Another object of the present invention is to afford a change-speedmechanism that is automatic in character and which is capable ofmanufacture at a reasonable cost.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment of the present invention and the principle thereof and what Inow consider to be the best mode in which I have contemplated applyingthat principle. Other embodiments of the invention embodying the same orequivalent principle may be used and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention and the purview of the appended claims.

In the drawings:

Fig. 1 is a horizontal sectional view through a power unit embodying atransmission mechanism constructed in accordance with the presentinvention;

Fig. 2 is an enlarged horizontal cross sectional view showing the powertransmission mechanism;

Fig. 3 is a vertical sectional View taken sub.

stantially along the line 33 of Fig. 2;

Fig. 4 is a sectional view taken substantially along the line 44 of Fig.2;

F g. 5 is a sectional view taken substantially along the line 55 in Fig.2; and I Fig. 6 is a fragmental side elevational view of the reactionplate of the transmission mechanism.-

For purposes of disclosure the present invention is illustrated asembodied in a power unit 2| that is located primarily within theperiphery of a wheel FW and which power unit is operable. to impartrotative driving force to the wheel FW. The power unit 2! as hereinillustrated is in many of its aspects similar in form and construction.

to the power unit shown in my aforesaid co-pending application, andreference may be had to such co-pending application for these details ofconstruction and relationship. In the present instance, it is suflicientto point out that the wheel FVV is rotatably mounted on an axle 22 thatextends laterally or horizontally in one di rection from one side of acenter strut 23 which,

as described in my aforesaid co-pending application, may extend upwardlyand may be mounted in the steering column of a bicycle or tricycl frameso that the wheel FW'constitutes the front wheel of such a vehicle. Onthe other or opposite side of the center strut as an engine 2| E ismounted and this is accomplished by securing one Wall of a crank case 24to the center strut 23 as described in my aforesaid co-pendingapplication. The engine 2IE is of the internal combustion type andserves to drive a crank shaft 25 that extends outwardly from the otherside of the crank case 24 and into a transmission housing 26 that isformed in part by a wall 26W and in part by a wall of the crank case 24and an extension 24W of such wall.

The present invention is concerned with the power transmission andcontrol between the from the unit shown in my aforesaid co-pending'application. Thus it will be observed that within the transmissionhousing 26, the crank shaft 25 has a sprocket 28 fixed thereon andachain 29 connects this sprocket with a sprocket 30 that is fixed on thedriven member of a primarycentrifugal clutch 32 that forms an element ofthe transmission of the present invention. The sprocket 32 is mounted ona drive plate 32D that forms the driving element of the clutch 32, andthis clutch also has a clutch drum 32E that is fixed on an output shaft35. The output shaft 35 serves as the driving element of a changespeedgear mechanism 36, the output element 3'! of which has a sprocket 38thereon that is conheated by a chain 39 to a sprocket 4!! fixed to thewheel FW so that the wheel FW may be driven by the power transmissionfrom the engine ME.

The primary clutch 32 is disclosed in detail in my co-pendingapplication, Serial No. 239,789, filed August 1, 1951, and reference maybe had to such co-pending application for details of structure andoperation of this primary clutch. It may pointed out, however, that thisprimary clutch is arranged to engage gradually and at a relatively lowspeed and embodies means which maintain the primary clutch 32 in itsengaged relationship until the speed of the clutch 32 has reducedsomewhat below its initial engagement speed, this being particularlytrue where the clutch is operating under load.

The clutch 32 has a driving element 32D thereof, mounted on a drivingshaft 65 that is supported by ball bearings 46 in the wall 26W of thetransmission housing, and the driven shaft 35 has its right-hand end, asviewed in Fig. 2, rotatably supported within a recessed end of thedriving shaft by means including a needle bearing 41'. The shaft 35extends to the left from the needle bearing 41 and has a clutch drum 48keyed thereto, such clutch drum constituting the driven element of theclutch 32. To the left of the clutch drum 48, as viewed in Fig. 2, theshaft 35 extends through a bearing sleeve 58 that is formed in a bearingplate 5! which is secured by means of cap screws 52 across an opening inthe extension 24W of the crank case wall, and the mounting plate 51 isparallel to the wall 26V\7 of the transmission housing. The driven shaft35 is supported in the bearing sleeve by means of a pair of needlebearings 53, as will be evident in 2 of the drawings. It should beobserved that the sleeve 55 extends in both directions from the plateEl, these oppositely projecting portions of the sleeve 59 beingidentified as 50L and 50R in Fig. 2 of the drawings. Beyond the left endof the sleeve section 58L, variable speed transmission =unit 36 isoperatively associated with the shaft 35, as will now be described indetail.

Considered in a broad sense, the variable speed transmission 36 isafforded by a planetary gear system, the driving or transmitting ratioof which is arranged to be automatically varied and controlled by meansof a centrifugally engaged friction clutch 60 that is relatively largein diameter so that a large frictional area is afforded, and this isquite important in the present mechanism in that it permits proper andsmooth operation throughout a range of slippage of friction clutchelements. The effectiveness of this structure in this respect is due ina large part to the large radiating surface afforded in the largediameter friction clutch 60 whereby the heat caused by slippage may beeffectually dissipated. Considering the mechanism more specifically, itshould be observed that the planetary gear system embodies a sun gear 6|carried on and keyed to the shaft 35 just to the left of the sleevesection 50L, and this sun gear is arranged to mesh with a plurality ofplanet gears 62 that are rotatably mounted on studs 63 atcircumferentially spaced points on a planet carrier 64. This planetcarrier 64 is fixed to the output element 3! of the unit, and in thisrespect it will be noted that the output element 31 is in the nature ofa stepped sleeve having sections 31R and 31L. The shaft 35 also has astepped formation, the left one of which is identified as 35L and thissection 35L- is the smallest of the step-sections of this shaft. Thesection 31L of the output element 31 rotatably surrounds the section 35Land is held against displacement in a left-hand direction by a C-washeror ring 65 that is engaged with a suitable annular groove in the end ofthe shaft, and a prospective cap 56 encloses this ring. The section MLof the output element 31 serves as a mounting for the sprocket 33, whilethe section 31B, surrounds a somewhat larger section 35B of the shaft35, and a needle bearing 68 supports the output element 31 rotatablywith respect to the shaft 35.

In attaining the desired mounting of the planet carrier M on the outputelement 31, the right-hand end of the sleeve section E'iR is externallysquared as at MS, Fig. 3, and the planet carrier 64 has a complementalsquared opening E iS formed therein so that this planet carrier 55 maybe slipped into position on the squared section 37S so as to rotativelyconnect the planet carrier 65 and the driven element 31.

The planetary transmission also includes a ring gear H3 that surroundsand meshes with the several planet gears 62, and this ring gear 10 isrotatably supported in what amounts to a supporting housing 7 l. Thishousing is formed primarily by a pair of generally annular sheet metalstampings TIL and HR which at their outer edges are connected togetherby means ineluding a plurality of screws 72. The stamping 7 !L isarranged to have a drum-like annular section llL-l so that the twostampings 'HL and 7 IR at their innermost radial portions are spacedapart a considerable distance in an axial sense, and thus. an, annularchamber is formed within the housing in which portions of the planetcarrier and portions of the planet gears are housed along with the ringgear '78 which, as will be described, is rotatively interlocked with thehousing H. Thus, as will be evident in Fig. 3, the dru like section 2iL-i of the ring gear housing is formed with a plurality of transverseribs 'i ID at annularly spaced points, and the ring gear 79 has aplurality of complemental and outwardly projecting ribs or lugs iiD thatfit into the grooves formed on the inside surfaces of the ribs ND.

The ring gear housing H is rotatively supported so as to be centered atall times upon the axis of the shaft 35, and to accomplish this, abearing 15R in the nature of a ball bearing is interposed between theinner edge of the stamping "HR and the sleeve section 50L, while asecond ball bearing 15L is interposed between the inner edge of thehousing section 'HL and the sleeve section 37R of the output element 31.In the present instance, dust retaining rings HR. and L are providedoutwardly of the bearings 15R and 55L.

In Fig. 2 of the drawings, an arrow 80 is shown in respect to the shaft35 to indicate its forward direction of rotation, and when such rotationis imparted to the shaft 35 and the sun gear ill, the forces effectivein the planetary gear, when there is a retarding force or load on theoutput element 31, tend to rotate the ring gear is in a reversedirection, and means are afforded for preventing such reverse rotationof the ring gear III while at the same time permitting forward rotationof the ring gear when this is desired, as will hereinafter be described.In the transmission as herein shown, the means for preventing suchreverse rotation of the ring gear III are afforded by a plurality ofpawls 82 that are pivoted by means of studs 83 on the right-hand face ofthe housing section HR, it being noted that these pivot studs 83 areparallel to the axis of the shaft 35. The pawls 82 may thu pivotinwardly about their pivot studs 83 and against the outer edge of astationary or non-rotating abutment ring 85, such abutment ringhaving amounting flange 86 that is held in place against the left-hand face ofthe mounting plate 5I by the cap screws 52. The ring 85 is formed toafford a plurality of teeth SET,

and these teeth are separated by slots 85S. As

will be evident in Fig. 5, any reverse rotation of the ring gear housingII will cause one of the pawls 82 to enter one of the slots 85S so as toengage one of the teeth 85T, thus to hold the ring gear housing IIagainst reverse rotation. In this respect it will be observed that thespacing of the pawls 82 and the teeth 85 is such that only one of thepawls 80 will normally move into its effective position, it having beenfound that a single pawl will serve in attaining the desired restrainingaction, and by this arrangement a shorter range of possible reversemovement of the ring gear is attained. The several pawls 82 are urgedtoward their effective positions by individual leaf springs 81 that aresecured by rivets 88 in 'a mounting ring 89 that is drum-like incharacter and which is secured to the housing 10 by the screws I2 aswill be evident in Fig, 2 of the drawings. The ring 89 overlies theflange 86 of the abutment member 85 so as to afford a dust guard inrespect to the enclosed mechanism.

The friction clutch 60 has one element SllA that is fixed in a rotativesense with respect to the ring gear housing II while the other elementBIJB of the friction clutch is fixed in a rotative sense to the outputelement 31 so that by effecting frictional connection of the elements68A and 50B of the friction clutch BI), the ring gear 'IIJ maybedrivingly coupled to the output element 31 so as to rotate in a forward,direction with the output element 31'. When this takes place, the speedreducing action of the planetary gear housing is afforded.

- In affording the element 60B of the clutch 60, a generally drum-likemetal stamping 92 is afforded and at this outer edge this stamping has aflange 92F of cylindrical form which is located so that it completelysurrounds the clutch element 659A with a substantial annular space be-itween the flange 92F and the clutch element 60A. The stamping 92 has awall portion that extends radially inwardly and is secured by cap screws94 and a spacer ring 95 to a flange 96 that is formed on the drivenelement 3'! so that the stamping or housing element 92 is connected tothe driven element 3'! for rotation therewith. A pair of clutch plates91 and 98 are disposed within the flange 92F and on opposite sides ofthe clutch plate 90, and rings of clutch lining or friction mational asare fixed on opposite sides of the plate 9!] for effecting frictionaldriving connection between the disc 90 and the two clutch plates 91 and9 8. The clutch plates 51 and 98 are secured rotatively to the clutchhousing 92 by means of a plurality of headed bolts IGI, there beingthree of these bolts in the present instance, as will be evident in Fig.3 of the drawings. The bolts IOI extend through appropriate apertures inthe plate gear system is nullified and there is in effect a direct drivefrom the shaft to the output element 3?. In intermediate stages ofengagement of the friction clutch 5G,.or in other words when thefriction clutch Si is slipping, the speed of the ring gear Ill in aforward direction may vary in accordance with the degree of clutchslippage in an infinite sense between zero velocity in a forwarddirection and a velocity that is equal to the velocity of the drivenelement 37. This correspondingly produces an infinite and gradualvariation in the output speed between the maximum speed reduction of theplanetary gearing and a direct or one-to-o-ne drive through the unit 36.

Thus, the element A of the friction clutch is aiforded in part by aplate 90 of circular form that has a central opening therein whichsurrounds the drum-like portion TIL-I of the ring gear housing II, andalong the inner edge of this opening tooth-like projections are formedto cooperate with recesses 9iiB, Fig. 3, on portion I ILI and alsorecesses are formed to cooperatewith protuberances 26A on portion I'IL-Iwhereby, in effect, a splined inner connection with the eleadjacentclutch plate 98.

91 and through radial slots I92 in the plate 98 as shown in Fig. 2, andeach such bolt has a head IBIH that engages the left-hand or outer faceof the plate 91. The other or left-hand edge of each bolt extendsthrough an opening in the wall of the clutch housing 92 and has a nut ItIN fixed thereon so that these bolts iflI serve to limit the right-handdisengaging movement of the righthand clutch 91. Between the plates 97and 98 and surrounding the bolts IQI, a plurality of springs I03 areafforded, one such spring surrounding each of the bolts HM, and thesesprings I 03 serve to impart separating or clutch releasing forces tothe clutch plates 91 and 93.

The clutch 60 has clutch engaging forces applied thereto by acentrifugal action, and for this purpose a plurality of weights in theform of balls I05 are disposed in the clutch housing as between theclutch plate 98 and the opposed wall of the clutch housing 92, and thewall of the clutch housing 92 is formed with a sloping cam surface 820that is so arranged that when the balls m5 move outwardly from theirnormal inward positions of Fig. 2, such balls are forced along the camsurface 920 and to the right so as to impart clutch closing or engagingmovements to the These clutch weights or balls I65 are normally urged ina yielding or resilient manner toward their radially inward orinelfective positions, and this is accomplished in the present instanceby a restoring ring I88 that is generally in the form of a plate withits inner edge bent to somewhat conical relationship as at I980 so thatthe ring may bear toward the right in Fig. -2 against the balls I05without causing any sharp corners or edges to engage the balls I05.

The return ring I08 is urged resiliently toward the left in Fig. 2 or ina return direction by a plurality of expansivecoil springs I09 whichsurround bolts III] that extend through the clutch plates 91 and 98 andthrough slots IIBSS in the return plate in much the same manner as thebolts IBI. Three such bolts III] and springs I69 are afforded as will beevident in Fig. 3 of the drawings, and these bolts are held in place bythe action of their heads MI and nuts IIQN.

In the operation of the transmission mechanism that has been described,the primary clutch 32 is, of course, in disengaged relationship when theengine 2!.E is stopped, and the engine ZIE may be started through theuse of a kick-starter mechanism E23 that is shown in Figs. 1 and 2. Thiskick-starter mechanism iEii has the starter shaft thereof aligned withthe driving shaft 45, and the structure and operation of this startermechanism is disclosed in my co-pending application, Serial No. 239,790,filed August 1, 1951, now Patent #2,6l2,055. After the engine ZIE hasbeen started as aforesaid, the shaft 45 and the driving member 3213 ofthe clutch 32 are constantly rotated. So long as the engine ZIE operatesat or near its idling speed the rotative speed of the shaft 45 isinsufficient to cause engagement of the primary clutch 32. The actualspeed of engagement of this clutch may of course be selected at anypredetermined figure, but for purposes of the present description it maybe assumed that idling speed of the engine is such that the shaft tswill operate at somewhat less than 309 R. P. M. Under suchcircumstances, the clutch 32 is arranged to engage when the speed'of theshaft is increased to somewhat over 300 R. P. l\'l., and the engagementof the primary clutch 32 is in a practical sense, gradual so that themovement of the vehicle will be initiated in a smooth manner, and suchsmoothness of the vehicle starting movement is enhanced under thepresent invention by reason of the relatively low transmission ratiothat is initially attained through the action of the variable speed unit36.

When the shaft 35 is rotated by the engagement of the primary clutch 32,such rotation is effective through the planetary gear system to rotatethe output element 3? at a greatly reduced speed as compared with thespeed of the shaft 35. In the present instance the parts areproportioned to give approximately a three and onehalf to one reduction.When the operating speed of the shaft is is maintained relatively cioseto the speed on which the primary clutch 32 has engaged, the reducedrotative speed of the output element 1? will be such that the frictionclutch 65 will remain disengaged. When, however the engine speed isincreased to such a point that the speed of the output element 37 isapproximateiy 1160 R. P. M. the centrifugal force acting on the balls orweights is suflicient to initiate outward radial displacement of theballs hi5, and this initiates clutch engaging movement of the clutch.element As soon as there is a substantial frictional force actingbetween the clutch plates and as on the one hand and the clutch elementcan, these forces tend to drive the ring gear housing H and the ringgear H1 in a forward direction, and such forward driving forces increasegradually as the speed of the output element increases. Thus, there willbe some slippage in the clutch but the heat generated in such slippageis found to be unobjectionable since it is rapidly dissipated by thelarge area of the elements of the clutch 5353. As the clutch engagingforces increase the clutch 6s finally reaches a fully engagedrelationship where the ring gear it; is driven as a unit with the outputelement 3'5 and when this condition obtains, there is a one to one driverelationship between the input or driving shaft ie and the outputelement 3?.

An important aspect of the present invention resides in thecharacteristic of the primary clutch 32 which causes this primary clutchto retain its engaged relationship when operating under load at lowspeeds. Another characteristic that is important in the presenttransmission is that when the elements of the transmission are at rest,the input shaft #15 is free and may be utilized in imparting startingforces to the engine ZIE.

It will also be observed that due to the possibility of slippage in theclutch 69, the present transmission is in effect load controlled to asubstantial degree, and for this reason it has been found that highlysatisfactory acceleration characteristics are attained despite widelyvarying conditions of load.

From the foregoing disclosure, it will be apparent that the presentinvention affords an improved power transmission mechanism that issimple in character and which is adapted for use in those situationswhere the space limitations are quite restrictive. Moreover, thistransmission mechanism of the present invention affords a loadresponsive variable ratio in the drive so as to thereby improve theoverall performance characteristics of the power unit, even though arelatively small driving engine 2iE is utilized.

Thus, while I have illustrated and described the preferred embodiment ofmy invention, it is to be understood that there is capable of variationand modification, and I therefore do not wish to be limited to theprecise details set forth, but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

1. In a variable speed transmission, a main bearing sleeve, a main driveshaft mounted concentrically in said bearing sleeve and adapted to berotated in a forward direction, a driven member arranged coaxially withthe out-put end of said drive shaft and including a carrier for planetgears arranged concentrically about a portion of said drive shaft and ina rotative relation thereto, a sun gear fixed to and rotatable with saiddrive shaft, planet gears journaled on said carrier in mesh with saidsun gear, a ring gear encircling and meshed with the planet gears andconstituting a track about which the planet gears may be revolvablydriven as a unit by the sun gear to transmit motion from the drive shaftto said driven member and the planet carrier at a reduced speed relativeto said drive shaft when said ring gear is held against rotation in areverse direction, a cup-shaped housing mounted concentrically about androtatably relative to said driven member and main bearing sleeve andhaving an annular extension surrounding the rin gear to which the ringgear is connected for rotation therewith, means acting between said ringgear housing and an abutment ring carried by said main bearing sleeve tohold said ring gear housing and the ring gear against rotation only in areverse direction so as to constitute the ring gear a track for theplanet gears revolving as a unit as aforesaid, one disc-like clutcheieznent fixed to and extended radially outwardly of the outer side ofthe ring gear housing, another clutch element fixed to said drivenmember for rotation therewith and including a pair of spaced co-axialdisc-like plates disposed on opposite sides of the first-named clutchelement adapted to en gage the same and cause the ring gear and housingtherefor to rotate with said driven member, said other clutch elementalso including a plate spaced from said pair of annular plates to form aclutch housing in which are located a plurality of centrifugallyactuatable balls adapted to move radially outwardly within said housingtherefor when the second-named clutch element rotates with said drivenmember, and a cam surface afforded on the last-named plate adapted to socam said balls in their radial outward movement within said housing asto cause the second-named clutch element to gradually engage thefirstnamed clutch element and thereby cause the ring gear and itshousing to rotate in a forward direction with the planet carrier tocouple the driven member to said main drive shaft in a one-to-onedriving relation.

2. In a variable speed transmission, a main bearing sleeve, a main driveshaft mounted concentrically in said bearing sleeve and adapted to berotated in a forward direction from a main source of power, a drivenmember arranged coaxially with the front or out-put end of said driveshaft and including a carrier for planet gears arranged concentricallyabout a portion of said drive shaft in a rotative relation thereto, asun gear carried by said drive shaft to rotate therew th in a forwarddirection, planet gears rotatably mounted on said carrier and in meshwith said sun gear so as to be rotated in a reverse direction by the sungear, a ring gear encircling and in mesh with the planet gears so as totend to rotate in a reverse direction with said planet gears, acup-shaped housing supported on said driven member and said main bearingsleeve so as to surround the ring gear, means affording a connectionbetween the ring gear and said housing so that the two are rotatablyinterconnected, a toothed ring carried by said main bearing sleeve, aplurality of pawls mounted in said housing and adapted to engage saidtoothed ring to hold said housing and the ring gear therewith againstrotation only in a reverse direction so as to constitute the ring gear atrack about which the planet gears may revolvably travel as a unit in aforward direction with the sun gear to couple the drive shaft and drivenmember in a speed re- 10 ducing relation, one clutch element fixed toand projecting radially outwardly of the outer side of the ring gearhousing, another clutch element carried by said driven member forrotation therewith and including a pair of spaced front and rear platesdisposed on the front and rear sides of the first-named clutch elementto engage the same and cause the ring gear and its housing to rotate ina forward direction with said driven member, said other clutch elementalso including an additional plate spaced from one of said pair ofplates to form a housing in which are located a plurality ofcentrifugally actuatable balls adapted to move radially outwardly withinsaid housing therefor when the second-named clutch element is drivenwith said driven member, the last-named plate including a cam meansadapted to cam said balls in their radial outward movement against saidone of said pair of plates so as to cause said pair of plates includedin the second-named clutch element to gradually engage the first-namedclutch element and thereby rotate the ring gear and its housing in aforward direction to couple the driven member to said main drive shaftin a one-to-one driving relation.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 834,592 Sturtevant Oct. 30, 1906 1,082,028 Jones et al Dec.23, 1913' 1,416,996 Stucatur May 23, 1922 1,526,949 Barenyi Feb. 17,1925 1,559,259 Knapp Oct. 27, 1925 1,741,853 Lyman Dec. 31, 19291,781,925 Johnson Nov. 18, 1930 2,007,304 Padgett July 9, 1935 2,056,050Harris Sept. 29, 1936 2,151,950 Tyler Mar. 28, 1939 2,445,482 HodgsonJuly 20, 1948

